TGF-beta1 mediated systemic fibrosis in diabetes may be amenable to gene therapy if an acceptable mode of sequence delivery to endothelium can be developed. Recombinant adenoviral or adeno- associated viral vectors are powerful gene transfer tools, but their use as gene therapy vehicles is limited by an inability to easily and effectively transduce specific organs in vivo. For example, targeted organ transduction with free virus often necessitates traumatic invasive procedures with selective vascular occlusion to prevent as wash-out effect. To overcome these technical limitations, we postulated that complexing viral constructs to microspheres and injecting systemically would facilitate endothelial delivery of the adenoviral particles, promote gene transfer, and be well tolerated. For the first time, we have shown that this adenoviral-microsphere shuttle effectively transduces the endothelium of the glomerulus and mesentery. Thus, the purpose of this project is to further refine the adenoviral-microsphere shuttle, and use this method to treat TGF-beta1-mediated systemic fibrosis in experimental diabetes. The work has 3 specific aims: Aim number 1 will further characterize the adenoviral-microsphere shuttle by assessing duration of transgene expression, investigate the feasibility of biodegradable microsphere vehicles, and assess the transduction utility of adeno-associated viral-microsphere complexes. Aim number 2 will elucidate the role of the coxsackie-adenoviral receptor (CAR) in mediating adenoviral transduction. Defining the regulation of CAR may have important implications for designing future approaches to adenoviral based gene therapies. Aim number 3 will utilize the adenoviral- microsphere shuttle to deliver antisense oligonucleotide sequences targeting the type II TGF-beta1 receptor (TbetaR-II). Antagonizing the TbetaR-II in diabetes will disrupt the intensely prosclerotic autoinduction cascade by which TGF-beta1, amplifies it own expression and promotes fibrosis. Taken together, these studies will explore a novel approach to the gene therapy of diabetic fibrosis. The adenoviral-microsphere shuttle combines the powerful transduction utility of adenovirus with the endothelial targeting afforded by microspheres, and represents a fresh approach to gene transfer based therapies.